Aluminum alloy for producing roll-shaped products

ABSTRACT

The invention relates to an aluminium alloy for manufacturing rollform products comprising the following alloy constituent in weight percentages:  
                                        0.1 ≦ Si ≦ 0.5         0.15 ≦ Fe ≦ 0.5         0.05 ≦ Cu ≦ 0.25          0.8 ≦ Mn ≦ 1.4          0.4 ≦ Mg ≦ 1.3                                  
others in sum maximum 0.15, individually maximum 0.05, rest Al. Said aluminium alloy ensures the manufacture of rollform products with high stability in thin metal thicknesses.

This invention relates to an aluminium alloy for manufacturing rollformproducts, as well as a strip for rollform products.

Strips produced from the aluminium alloy according to the presentinvention are profiled in so-called rollformers into finished products,such as for example roller blind rods, skylights, panel and claddingstrips. From the prior art it is known to manufacture correspondingstrips for rollform products from the aluminium alloy AA 3005. Therequirements for a strip for rollform products are essentially bendingand buckling resistance, and therefore stability of the finishedprofiled product, in very good deformation properties even at criticalcurvature radii (with roller blind strips curvature radius t=0), verygood rollformability with very good lacque adhesion at the same time.

For weight and cost reasons strips with less thickness, =0.3 mm, areused increasingly to manufacture rollform products. With thesethicknesses the strips for rollform products, manufactured from thealloys known from the prior art, exhibit stability problems with respectto bending and buckling resistance.

Based on the aforementioned it is an object of the present inventionaccording to a first teaching to provide an aluminium alloy formanufacturing rollform products, which guarantees high stability of thefinished profiled product.

According to the first teaching of the invention the above mentionedobject is solved in that an aluminium alloy for manufacturing rollformproducts comprises the following alloy constituent in weightpercentages:  0.1 ≦ Si ≦ 0.5 0.15 ≦ Fe ≦ 0.5 0.05 ≦ Cu ≦ 0.25  0.8 ≦ Mn≦ 1.4  0.4 ≦ Mg ≦ 1.3

-   -   others in sum maximum 0.15, individually maximum 0.05, rest Al.

This aluminium alloy according to the first teaching of the inventionalso ensures high stability of the finished product even when thin metalthicknesses are employed. In addition, the alloy has excellentdeformation properties even at critical bending radii, very goodrollformability as well as very good lacque adhesion after formingoperation, due to a well and smooth metal surface.

According to a second teaching of the invention relates to a strip forrollform products, which is improved compared to the prior art in thatthe strip essentially comprises an aluminium alloy according to thefirst teaching of the invention. Regarding the advantages of theinventive strip for rollform products reference is made to thestatements relating the first teaching of the invention.

In that the grain of the strip comprises 2 to 10 casting phases per 1000μm² with a maximum size of 40 μm and an average length of 2 to 6 μm, 500to 1200 fine precipitations per 1000 μm² as well as residual resistanceswithin the range of 1.2 to 2.5 μohm, it is ensured that according to asecond teaching of the invention the strip has very good flexibility andpermits bending radii of t=0 without problems and moreover features avery good subsequent processing (=rollformability).

The second teaching of the invention grains a particularly advantageousdevelopment in that the strip comprises a coat of lacquer applied bycoil coating method. Such a coat of lacquer applied by coil coatingmethod has outstanding lacque adhesion, which ensures that the lacquedoes not detach respectively is not damaged during rollforming.

Furthermore, according to a third teaching of the invention theinvention relates to a method for producing a strip for rollformproducts, which is improved compared to the prior art, in that the stripis essentially made from an aluminium alloy according to claim 1.Regarding the advantages of the inventive method for manufacturingstrips for rollform products reference is made to the statementsrelating the first teaching of the invention.

According to a first development of the third teaching of the inventionan advantageous grain of the strip for rollform products is made in thatthe ingot is annealed during preheating of the warm rolling processwithin the temperature range of 480 to 610° C. for at least 3 hours.

This grain is further improved in that the strip is manufactured by warmrolling within the temperature range of 270 to 550° C.

There is now a large number of possibilities to further design anddevelop the inventive aluminium alloy for manufacturing rollformproducts, the inventive strip for rollform products or the inventivemethod for manufacturing a strip for rollform products. In this contextfor example reference is made on the one hand to the claims and on theother hand to the description of an embodiment for a rollform product inconjunction with the drawing.

In the drawing the sole FIGURE shows a partial perspective sectionthrough an embodiment of a rollform product manufactured from thealuminium alloy according to the present invention.

The rollform product illustrated in the sole FIGURE is a roller blindrod.

As is known from the prior art this roller blind rod is manufactured byrollforming from a strip for rollform products 1. This strip forrollform products 1 comprises an aluminium alloy according to thepresent invention having the following alloy constituents in weightpercentages:  0.1 ≦ Si ≦ 0.5 0.15 ≦ Fe ≦ 0.5 0.05 ≦ Cu ≦ 0.25  0.8 ≦ Mn≦ 1.4  0.4 ≦ Mg ≦ 1.3

-   -   others in sum maximum 0.15, individually maximum 0.05, rest Al.

The cavity of the roller blind rod illustrated in the sole FIGURE isfilled by a synthetic foam 2 in the illustrated embodiment.

The critical deformation with a curvature radius of t=0 is to be seenparticularly clearly at position 3. The aluminium alloy according to thepresent invention ensures such critical deformation on the finishedlacquered product.

In addition, use of the aluminium alloy according to the presentinvention also ensures good stability of the roller blind rod in metalthicknesses under 0.3 mm.

The manufacture of the strip for rollform products 1 takes placestarting with the ingot made of the aluminium alloy according to thepresent invention by preheating within the temperature range of 480 to610° C. at a dwell time of at least 3 hours, warm rolling within thetemperature range of 270 to 550° C., cold rolling and heat treatment.

The strip for rollform products comprises the following mechanicalproperties after lacquering:

-   -   Tensile strength: Rm 240-280 N/mm²    -   Yield point: Rp>215 N/mm²    -   Elongation at break: ASO>6%.

The desired grain is created by manufacturing the strip by continuouscasting of a rolling ingot, ingot preheating within the temperaturerange of 480 to 610° C. and warm rolling within the temperature range of550° C. to 270° C. The grain of the strip is characterised by a numberof casting phases, also known as coarse precipitations, within the rangeof 2 to 10 per 1000 μm² with a maximum size of 40 μm and an averagelength of 2 to 6 μm. The strip also has fine precipitations of less thanapproximately 1 μm, which number is within the range of 500 to 1200 per1000 μm².

Finally the dissolution state of the strips is characterised by residualresistances within the range of 1.2 to 2.5 μohm cm. The residualresistance is measured at a helium temperature of 4.2 K.

1. A use of an aluminium alloy for manufacturing roll-formed productscomprising the following alloy constituent in weight percentages:  0.1 ≦Si ≦ 0.5 0.15 ≦ Fe ≦ 0.5 0.05 ≦ Cu ≦ 0.25  0.8 ≦ Mn ≦ 1.4  0.4 ≦ Mg ≦1.3

others in sum maximum 0.15, individually maximum 0.05, rest Al.
 2. A useof a strip for rollform products, wherein the strip is made from analuminium alloy according to claim
 1. 3. A use of a strip for rollformproducts according to claim 2, wherein the grain of the strip comprises2 to 10 casting phases per 1000 μm² with a maximum size of 40 μm and anaverage length of 2 to 6 μm, 500 to 1200 fine precipitations per 1000μm² as well as residual resistances within the range of 1.2 to 2.5 μtohmcm.
 4. A use of a strip according to claim 2, wherein the stripcomprises a coat of lacquer applied by coil coating method.
 5. A methodfor manufacturing a strip for rollform products, wherein the strip isessentially made from an aluminium alloy according to claim
 1. 6. Themethod for manufacturing a strip for rollform products according toclaim 5, wherein the ingot is annealed during preheating of the warmrolling process within the temperature range of 480 to 610° C. for atleast 3 hours.
 7. The method for manufacturing a strip for rollformproducts according to claim 5 or 6, the strip is manufactured by warmrolling in the temperature range of 270 to 550° C.